Very basic intro, typescript types

readme.md

Typescript getting started

Let's get started with Typescript.

We will use Typescript online playground for this demos:

http://www.typescriptlang.org/play/

Steps

• Let's start with something very basic, if we paste this code on codepen (javascript):

let a = 3;
let b = 5;

b= "5";

const result = a + b;

console.log(result);

Instead of getting 8 as expected result, we will get the following result: 35

• Let's paste this code into typescript playground and we will notice that we get type checking for free.

Type already infers that a and b vars are typed (number) and throws an error indicating that the b assignment "5" is wrong.

• We can be more explicit and define the types:

- let a = 3;
+ let a : number = 3;
- let b = 5;
+ let b : number = 5;

b= 5;

const result = a + b;

console.log(result);